Anna Rita Bentivoglio, MD, PhD, from the Catholic University in Rome, and colleagues followed nine patients with Parkinson's disease who had a quadripolar electrode strip extradurally implanted over the motor cortex and received continuously delivered stimulation to the most affected clinical side. Patients were assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) and the Parkinson's Disease Quality-of-Life Questionnaire.

The researchers found that there were no surgical complications or adverse events and there were no cognitive or behavioral changes observed. At one, three, six, and 12 months, respectively, the UPDRS III at baseline was decreased by 14.1, 23.3, 19.9, and 13.2% under the off-medication condition. Three to four weeks after stimulation, the bilateral motor effects appeared and outlasted the stimulation itself for three to four weeks in one case of the stimulator accidental switching off. There were decreases of 40.8, 42.1, and 35.5% at one, three, and 12 months, respectively, for the UPDRS IV. There was an increase in the scores of the Parkinson's Disease Quality-of-Life Questionnaire at three, six, and 12 months.

"Extradural motor cortex stimulation is a safe procedure," the authors write. "However, the short follow-up and limited beneficial effects suggest the need for further investigation of the actual effects of extradural motor cortex stimulation on the clinical conditions of Parkinson's disease patients."

Several authors disclosed financial ties to the health care and medical technology industries.